The precipitation of kraft lignin with poly(diallyldimethylammonium chloride), poly(DADMAC), was characterized as a function of pH. At a mass mixing ratio of poly(DADMAC) to lignin of 0.53 at pH 12.6, approximately 80% of the added lignin was removed, whereas the precipitate contained less than 35% of the added poly(DADMAC). Lignin precipitated with as much as 75% of the charges not associated with poly(DADMAC). Lower pH solutions required less poly(DADMAC) for lignin precipitation. Colloidal complex formation was measured as a function of time by dynamic light scattering, and the results could be fitted by a diffusion-controlled aggregation model.

Properties of Poly(DAMAC):

Water soluble cationic polymer. High cationic charge density in ready to use aqueous solution form. Material is quaternized cyclic amine supplied as the quarternary amine chloride.

The ability to modify surfaces and provide cationic character allows the user to selectively attract negatively charged functional groups to the coated surface or to the dissolved water soluble cationic polymers.